Complexes generated in situ from Rh（CO）2 （acac）+diphosphine are found to bevery efficient homogeneous catalysts for the hydrogenation of α,β-unsaturated aldehydes andketones into the corresponding saturated carbonyl compounds.In the presence of the chiraldiphosphine（-）-diop,geranial is hydrogenated into（+）-citronellal with optical yield 62%e.e.and neral into（-）-citronellal with 55% e.e.respectively.
